JP2001026105A - Ink jet head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an ink jet head in which an electrode substrate can be employed for taking out a common electrode while reducing the size of the head and variation in the ink drop ejection characteristics is suppressed among bits by providing an electrode on a conductive electrode substrate through an insulating layer and connecting the electrode substrate electrically with a diaphragm. SOLUTION: An electrode substrate 2 is made of a conductive silicon substrate having polarity matching that of a diaphragm 10. An insulating layer, i.e., a silicon oxide film 22, is formed on the wall face of a recess 21 and an electrode 23 is provided oppositely to the diaphragm 10 on the bottom face of the recess 21 thus placing the electrode 23 on the electrode substrate 2 through the insulating layer. A gap 24 is formed between the diaphragm 10 and the electrode 23 constituting an actuator part. An insulating film 25, e.g. an SiO2 film, is formed on the surface of the electrode 23 which is led out to form an electrode pad part 26. A plurality of nozzle holes 4 are made through a nozzle plate 3 and ink supply openings 15 are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet head, and more particularly to an electrostatic ink jet head.

[0002]

2. Description of the Related Art An ink jet head used in an ink jet recording apparatus used as an image recording apparatus (image forming apparatus) such as a printer, a facsimile, a copying apparatus, a plotter, etc. has a nozzle hole for discharging ink droplets and this nozzle hole communicates. A discharge chamber (also referred to as a pressure chamber, a pressurized chamber, a pressurized liquid chamber, a liquid chamber, an ink flow path, etc.) and an energy generating means for generating energy for pressurizing the ink in the discharge chamber; By driving the energy generating means, the ink in the ejection chamber is pressurized to eject ink droplets from the nozzle holes, and the ink-on-demand type, which ejects ink droplets only when recording is necessary, is mainly used. is there.

Conventionally, as an energy generating means for generating energy to pressurize ink in a discharge chamber, a piezoelectric element is used to deform a diaphragm forming a wall surface of the discharge chamber to change the volume of the discharge chamber to discharge ink droplets. (See JP-A-2-51734), or an ink droplet is ejected by pressure generated by heating ink in an ejection chamber using a heating resistor to generate bubbles. Japanese Patent Application Laid-Open No. 61-59911) is known.

However, in the former method using a piezoelectric element, the process of attaching the chip of the piezoelectric element to the diaphragm in order to generate pressure in the discharge chamber is complicated, and there are limits to high speed and high printing quality. However, in the latter method of heating ink, although the problem of using a piezoelectric element does not occur, the heating resistor is rapidly damaged by repeated heating and cooling of the heating resistor, and the shock when the bubbles disappear, because the heating resistor is damaged. In addition, there is an inconvenience that the life of the inkjet head is shortened as a whole.

In order to solve such a problem, as described in Japanese Patent Application Laid-Open No. Hei 6-71882, a diaphragm forming the wall surface of a discharge chamber and an electrode are arranged in parallel with each other. The gap formed is referred to as a “parallel gap”.) An ink jet head that ejects ink droplets by changing the volume of a discharge chamber by deforming the diaphragm by electrostatic force generated between the diaphragm and the electrode is proposed. Have been.

[0006] As shown in FIGS. 10 and 11, a conventional electrostatic ink jet head includes a pressurizing chamber 10 on a substrate 101.
2. While forming a diaphragm 103 forming the wall surface of the pressure chamber 102, a common ink chamber 104 for supplying ink to the pressure chamber 102, an ink supply path 105 connecting the common ink chamber 104 and the pressure chamber 102, and the like. A silicon oxide film 112 is formed on an electrode substrate 111 made of a borosilicate glass substrate or a silicon substrate. An electrode 113 is formed on the silicon oxide film 112 so as to face the vibration plate 103. Then, the substrate 101 and the electrode substrate 111 are joined via a silicon oxide film 112. Further, a nozzle plate 121 is bonded on the substrate 101, and the nozzle plate 121 is formed with a nozzle hole 122 communicating with the pressurizing chamber 102 and an ink supply port 123 for supplying ink to the common ink chamber 104.

In order to use the diaphragm 103 as a common electrode, as shown in FIG. 10, a common electrode electrode extraction region 106 is provided at the end of the substrate 101 in the nozzle arrangement direction, and the electrode 113 is used as an individual electrode. The electrode pad 116 is drawn out to the end side of the electrode substrate 111 to form an electrode pad 116, and the substrate 101 on the electrode pad 116 is opened.

[0008]

As described above, in the conventional electrostatic ink jet head, an electrode extraction region must be provided in order to use the diaphragm as a common electrode. Inviting. Further, since the gap between the diaphragm and the electrode is formed by using the silicon oxide film as a gap spacer as it is, it is difficult to control the gap over a wide range, and the desired head operation (vibration)
There is also a problem that it is difficult to design according to characteristics.

The present invention has been made in view of the above points, and has as its object to reduce the size of a head and reduce variations in vibration characteristics.

[0010]

In order to solve the above-mentioned problems, an ink jet head according to the present invention is provided with an electrode facing a diaphragm via an insulating layer on an electrode substrate having conductivity. The diaphragm and the diaphragm are electrically connected.

Here, the electrical connection between the electrode substrate and the vibration plate can be made by bonding the electrode substrate to the vibration plate without an insulating layer. In this case, the electrode substrate and the vibration plate can be formed from a silicon substrate and both silicon substrates can be directly bonded, or the electrode substrate and the vibration plate can be formed from a silicon substrate and both silicon substrates can be shared via a metal. Can be crystal bonded.

In this case, the crystal orientation (10
0) Single crystal silicon substrate or crystal plane orientation (110)
It is preferable to use a single-crystal silicon substrate.

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an explanatory plan view of an inkjet head according to a first embodiment of the present invention, and FIG.
3 is a sectional view taken along line AA of FIG. 1, FIG. 3 is a sectional view taken along line BB of FIG. 1, and FIG. 4 is a sectional view taken along line CC of FIG.

The ink jet head includes a vibration plate / liquid chamber substrate 1, an electrode substrate 2 provided below the vibration plate / liquid chamber substrate 1, and a nozzle plate provided above the vibration plate / liquid chamber substrate 1. 3, a plurality of nozzle holes 4 for ejecting ink droplets,
A pressurizing chamber 6, which is an ink flow path communicating with each nozzle hole 4, and a common ink chamber 8, which communicates with each pressurizing chamber 6 via a fluid resistance portion 7 also serving as an ink supply path, are formed.

The diaphragm / liquid chamber substrate 1 uses a silicon substrate such as a single-crystal silicon substrate, a polycrystalline silicon substrate, or an SOI substrate. A concave portion 11 forming a vibration plate (first electrode) 10 to be formed, a groove 12 forming a fluid resistance portion 7, and a concave portion 13 forming a common ink chamber 8 are formed.

The electrode substrate 2 is a conductive substrate (here, a silicon substrate having the same polarity as the vibration plate 10), and has a recess 21 formed therein.
A silicon oxide film 22 as an insulating film (insulating layer)
Is formed on the bottom surface of the concave portion 21 and the electrode 2 facing the diaphragm 10 is formed.
3, the electrode 10 is provided on the electrode substrate 2 via an insulating layer.
Is provided, a gap 24 is formed between the diaphragm 10 and the electrode 23, and the diaphragm 10 and the electrode 23 constitute an actuator section. Then, an insulating film (protective film) 25 such as an oxide film or a nitride film such as a SiO ₂ film is formed on the surface of the electrode 23, and the electrode pad portion 26 is formed by extracting the electrode 23.

Here, a concave portion 21 having a vertical wall surface (long-side wall surface) is formed by anisotropic etching by wet etching by using a single crystal silicon substrate having a crystal plane orientation (110) as the electrode substrate 2. By forming the electrode 23 in such a concave portion 21,
The area of the electrode facing the diaphragm 10 can be increased, the capacitance can be increased, and stable vibration characteristics can be obtained.

The vibration plate / liquid chamber substrate 1 and the electrode substrate 2
By using a single-crystal silicon substrate and joining the two substrates 1 and 2 by direct bonding or eutectic bonding via a metal, the electrode substrate 2 and the diaphragm 10 are insulated as shown in FIG. They are joined and electrically connected without any layers.

The nozzle plate 3 is provided with a plurality of nozzle holes 4
An ink supply port 15 for supplying ink from outside to the common ink chamber 8 is formed. A water-repellent surface treatment layer is formed on the ink ejection surface of the nozzle plate 3.

In the ink jet head configured as described above, the vibration plate 10 is electrically connected to the electrode substrate 2, which is a conductive substrate, without the interposition of an insulating layer. As described above, by grounding the electrode substrate 2, the potential of the diaphragm 10 is also grounded (0 V), and the diaphragm 10 can be used as a common electrode. Therefore,
When a driving voltage is applied between the electrode 23 serving as an individual electrode and the diaphragm 10, the diaphragm 10 is deformed and displaced by electrostatic force, the inner volume of the pressurizing chamber 6 is changed, and the ink Drops are ejected.

In this case, as the displacement driving method of the diaphragm, the diaphragm 10 is displaced toward the electrode 23 without being brought into contact with the electrode 23, and the diaphragm 10 is discharged from this state to discharge.
The non-contact drive method of ejecting ink droplets by returning the vibration plate 10 is displaced until the diaphragm 10 contacts the electrode 23,
Any of the contact driving methods of discharging ink droplets by discharging from this state and returning the vibration plate 10 can be adopted.

As described above, the electrodes are provided on the conductive electrode substrate with the insulating film interposed therebetween, and the electrode substrate is joined to and electrically connected to the diaphragm without the interposition of the insulating film. An electrode lead-out region for making the common electrode a common electrode can be omitted, and the head can be miniaturized. Further, since the potential for the common electrode can be obtained in a wide range on the back surface of the electrode substrate, it is possible to reduce the variation in the ink droplet ejection characteristics due to the variation in the potential between each bit (between the nozzles).

The electrical connection between the electrode substrate and the vibration plate can be stably obtained with high reliability by joining the electrode substrate and the vibration plate without using an insulating layer. . Needless to say, the electrode substrate and the vibration plate can be joined via the insulating layer to separately electrically connect the electrode substrate and the vibration plate.

Next, an ink jet head according to a second embodiment of the present invention will be described with reference to FIG. The ink jet head is formed by performing anisotropic etching by wet etching on the concave portion 21 using a silicon substrate having a crystal plane orientation (100) as the electrode substrate 2.

In this case, since the concave portion 21 has a wall surface which becomes an inclined surface of about 54 degrees, the interval of the gap 24 is gradually changed by forming the electrode 23 in the concave portion 21. Note that a gap formed between the non-parallel diaphragm and the electrode is referred to as a “non-parallel gap”.

Since the electrostatic force generated between the diaphragm 10 and the electrode 23 is inversely proportional to the square of the distance (distance) between the two, the desired electrostatic force can be obtained at a lower voltage as the distance between the electrodes is smaller. Can be. Therefore, the diaphragm 10 is deformed and displaced from the region where the distance to the electrode 23 is small due to the gradual change of the interval of the gap 24, and the distance between the diaphragm 10 and the electrode 23 is correspondingly reduced. It becomes possible to drive with voltage.

Next, an ink jet head according to a third embodiment of the present invention and its manufacturing process will be described with reference to FIGS.
This will be described with reference to FIG. 6 and 7 are cross-sectional views in the longitudinal direction of the head, and FIGS. 8 and 9 are cross-sectional views in the lateral direction of the head.

First, as shown in FIGS. 6A and 8A, the crystal plane orientation (110) or (1)
A silicon oxide film 32 serving as a protective film is formed on the surface of the p-type single crystal silicon substrate
m to form a film. Here, a low-cost p-type single-crystal silicon substrate is used, but an n-type silicon substrate can also be used. However, the silicon substrate 31 serving as the electrode substrate 2 and the diaphragm 10 have the same polarity.

Subsequently, as shown in each figure (b), a silicon nitride film 33 serving as an etching barrier layer in a later step is formed on the surface of the silicon oxide film 32 to a thickness of about 100 nm by a method such as LP-CVD or thermal CVD. It is formed with a thickness. Next, as shown in each figure (c), patterning for electrode formation is performed by using a photo-etching technique, and the silicon nitride film 33 and the silicon oxide film 32 are formed using the photoresist film as a mask. Etching is sequentially performed to form a pattern in which a region for forming the electrode 23 is opened.

Next, this substrate 31 is washed with a high-concentration potassium hydroxide solution (for example, 30% KOH heated to 80 ° C.).
Solution)), and anisotropic etching of silicon is performed to engrave a desired concave portion 21 in the silicon substrate 31. At this time, the groove depth of the concave portion 21 is determined by a gap size necessary for driving the diaphragm 10, a thickness of the electrode protective film 25 and the electrode 23, and a silicon oxide film for insulating the silicon substrate 31 and the electrode 23. Engrave only 22 thickness.

In this case, the etching was performed using a high-concentration aqueous solution of an alkali metal.
For example, wet etching using methyl, ammonium, or hydroxide may be used. Although it takes time, a groove (recess) may be formed by dry etching.
However, in the case of dry etching, the gap control using the plane anisotropy of the etching rate as in the above-described second embodiment cannot be performed.

Next, the silicon substrate 3 after the groove processing is completed
After cleaning 1, as shown in each figure (d), the entire silicon substrate 31 is heat-treated to form a silicon oxide film 22 serving as an insulating film in the concave portion 21 where silicon is exposed. The thickness of the silicon oxide film 22 may be any thickness as long as the individual electrodes 23 and the silicon substrate 31 can be electrically insulated. Here, the thickness is about 1 μm, assuming that the individual electrodes 23 are connected by wire bonding. At this time, the silicon nitride film 33 is
Remain, the silicon oxide film 32 does not grow and is kept in a thin state.

Subsequently, as shown in each figure (d), a polycrystalline silicon film serving as an electrode material is deposited to a thickness of about 300 nm, and processed into a desired electrode shape using a photo-etching technique. 23 are formed. Here, polysilicon doped with impurities is used for the electrode, but a high melting point metal may be used, or a conductive ceramic such as titanium nitride may be used for the electrode.

Thereafter, the silicon substrate 31 was thermally oxidized to form an oxide film 25 on the surface of the polysilicon electrode 23, thereby forming an electrode protection film. Here, when titanium nitride is used, an electrode material is deposited, a silicon oxide film such as HTO is deposited, an electrode shape is formed on the silicon oxide film by a photo-etching method, and this pattern is used as a mask. The electrode 23 may be formed by sequentially etching the material.

Subsequently, although not shown, the silicon substrate 31
The silicon nitride film 33 remaining on the upper surface is selectively removed by etching. After the nitride film 33 is removed, the silicon oxide film 3 on the surface of the silicon substrate 31 is formed using thin hydrofluoric acid.
Remove 2 completely. At this time, the silicon oxide film 25 on the electrode 23 is also etched, but there is no problem because the silicon oxide film 25 is sufficiently thicker than the oxide film 32 on the silicon substrate 31 serving as a bonding surface. However, since a natural oxide film is formed in a short time on the silicon substrate 31 from which the oxide film 32 has been removed, it is necessary to remove the oxide film 32 immediately before bonding with the silicon substrate serving as the diaphragm / liquid chamber substrate. is important.

Then, after the oxide film 32 of the silicon substrate 31 is removed, as shown in FIGS. 7A and 9A,
A silicon substrate 41 serving as the vibration plate / liquid chamber substrate 1 is bonded on the silicon substrate 31.

Here, as the silicon substrate 41, a p-type double-side polished silicon substrate having a crystal plane orientation (110) is used. Such a silicon substrate is used in order to obtain a good surrounding shape by utilizing the plane anisotropy of the etching rate during wet etching of silicon.

A high-concentration boron is implanted (1 × 10 ²⁰ atoms / cm ³ or more) into the bonding surface side of the silicon substrate 41.
This is activated to form the boron diffusion layer 42 diffused to a predetermined depth, that is, the thickness of the diaphragm 10. Here, a silicon substrate into which a high-concentration impurity is implanted is used. However, for example, an active layer of an SOI substrate can be used as a diaphragm, and silicon is epitaxially deposited on the high-concentration impurity substrate. The grown substrate can be used as a diaphragm. As long as the polarity of the diaphragm and the polarity of the electrode substrate match, any substrate can be used.

The silicon substrate 31 and the silicon substrate 4
First, both substrates 31 and 41 are cleaned by SC-1 cleaning method (a mixed solution of ammonia water + hydrogen peroxide water + ultra pure water is applied for 8 minutes).
Wash in solution heated above 0 ° C. ). Subsequently, the substrate is washed with thin hydrofluoric acid to remove the oxide films on the silicon substrates 31 and 41. By this treatment, all the oxide film on the surface can be removed, and the silicon interface can be terminated with hydrogen atoms. As a result, the bonding surfaces of the silicon substrates 31 and 41 have water repellency. By this processing, the conductivity of the silicon surface can be secured.

Therefore, the surfaces of these substrates 31, 41 are gently aligned and bonded. At this time, since the substrates 31 and 41 have only a weak self-bonding force such as an intermolecular force, they are temporarily fixed by pressing with a pressure of 1 to 2 bar. Thereafter, under a nitrogen atmosphere, 800 to 1100 ° C.
By firing the substrate for about 2 hours at 1000 ° C., the two substrates 31 and 41 can be directly bonded. By this heat treatment, both substrates 31, 41
Are firmly fixed, and the required bonding strength can be obtained.

Subsequently, the bonded silicon substrate 41 is completed.
Then, a thin diaphragm 10 and a recess for a liquid chamber are formed. First, an LP-CVD method and a heat C
The silicon nitride film 43 is formed to a thickness of about 500 n by a method such as a VD method.
m. The thickness of the silicon nitride film 43 at this time may be any thickness as long as it functions as a mask during etching in a later step.

Then, the silicon substrate 4 forming the diaphragm
On one side, a photoresist is applied and a pattern aligned with the electrode pattern in the bonding surface is formed using infrared light or the like, and the silicon nitride film 43 is removed in accordance with the photoresist pattern. Silicon nitride film 4 having an opening corresponding to the depression for the pressure chamber and the depression for the common ink chamber
The pattern of No. 3 is formed.

Thereafter, the bonded silicon substrates 31,
41 is a high-concentration potassium hydroxide solution (for example, 80 ° C.)
(A 30% KOH solution heated to a predetermined temperature) and anisotropically etching the silicon substrate 31 as shown in FIG.
4. A recess 45 serving as a common ink chamber 8 is formed, and a groove (orifice) 46 serving as a nozzle communication passage and a fluid resistance portion 7 are formed.
Is formed.

At this time, since the silicon nitride film 43 is formed over the entire surface of the silicon substrate 41 by forming the silicon nitride film 43 by the CVD method, the silicon substrate 41 is immersed in a potassium hydroxide solution. However, other than the predetermined pattern surface is not etched. Then, when the etching proceeds to the diffusion layer 42 in which the impurities are diffused at a high concentration, the etching rate is reduced to a state where the etching is almost completely stopped. As a result, the diaphragm 10 having a desired thickness and made of the diffusion layer 42 can be obtained with high accuracy. This has the advantage that the conditions such as the etching time management can be determined gently and the process management can be easily performed.

Subsequently, the bonded silicon substrates 31, 41 after the etching are washed, and if necessary, the silicon nitride film remaining on the surfaces of the bonded substrates 31, 41 is selectively removed. As shown in c), a portion of the silicon substrate 41 serving as an outlet for an individual electrode is opened using an etching mask, and then cut into individual inkjet heads. After that, the lid member 49 having the ink supply port 15 is bonded onto the silicon substrate 41.

As a result, as shown in FIG. 4C, the diaphragm / liquid chamber substrate 1 is formed from the silicon substrate 41, the electrode substrate 2 is formed from the silicon substrate 31, and the nozzle end face (side wall) is formed on the head end face (side wall). An ink jet head having a hole 4, a pressurizing chamber 6 communicating with the nozzle hole 4 via a nozzle communication passage 4 a, a vibration plate 10 forming a wall surface of the pressurizing chamber 6, an electrode 23 opposed thereto, and the like are provided. Complete.

Then, the head connects the individual electrodes 23 on a holding substrate (a mounting substrate such as a glass epoxy substrate) by wire bonding, and takes out a common electrode from the back surface of the silicon substrate 31 which is the electrode substrate 2.

By adopting such a configuration, it is possible to stably supply the potential of the diaphragm, and it is possible to suppress the variation in the vibration characteristics between the bits.

Next, another method of manufacturing the ink jet head according to the third embodiment of the present invention will be described. Here, the silicon substrate 4 serving as the vibration plate / liquid chamber substrate described above is used.
1 and a silicon substrate 31 serving as an electrode substrate are joined by eutectic joining. Note that the other steps are the same as those in the above-described manufacturing process, and thus the description is omitted.

That is, first, both substrates 31 and 41 are
-1 Washing method (washing a mixed solution of ammonia water + hydrogen peroxide + ultrapure water in a solution heated to 80 ° C or higher). Subsequently, the substrate is washed with thin hydrofluoric acid to remove the oxide films on the silicon substrates 31 and 41. By this treatment, all the oxide film on the surface can be removed, and the silicon interface can be terminated with hydrogen atoms. As a result, the bonding surfaces of the silicon substrates 31 and 41 have water repellency. By this processing, the conductivity of the silicon surface can be secured.

Subsequently, gold, which is a metal causing a eutectic reaction with silicon, is applied to the surface of the silicon substrate 41 to be a bonding surface by about 1 μm.
Deposit to a thickness of m. Here we use gold,
Any metal that causes a eutectic reaction with silicon may be used instead of gold, for example, an alloy of Sn, Pb, Ge, and gold.

Thereafter, the silicon substrates 41 and 31 were bonded and fixed with a fixing jig, and then baked at 400 ° C. for 1 hour in a nitrogen atmosphere to bond the wafers together. This heat treatment causes a eutectic reaction between gold and silicon, and forms a liquid layer at a low temperature of about 370 ° C. to be in a eutectic state. When silicon further diffuses, the composition goes out of the composition range showing the eutectic reaction. At such a low temperature, a liquid layer cannot be formed and the reaction stops.
As a result, the silicon substrate 31 and the silicon substrate 41 are integrated and a strong bond is obtained.

[0053]

As described above, according to the ink jet head of the present invention, electrodes are provided on a conductive electrode substrate via an insulating layer, and the electrode substrate and the diaphragm are electrically connected. Therefore, the electrode substrate can be used for taking out the common electrode, the size of the head can be reduced, and the variation in the ink droplet ejection characteristics between bits can be reduced.

Here, by joining the electrode substrate to the diaphragm without the interposition of the insulating layer, the electrode substrate and the diaphragm can be electrically connected stably and with high reliability. in this case,
By forming the electrode substrate and the vibration plate from a silicon substrate and directly bonding the two silicon substrates, warpage or peeling due to a difference in thermal expansion does not occur, and gap accuracy can be secured. In addition, since the electrode substrate and the diaphragm are formed from a silicon substrate and both silicon substrates are eutectic bonded via a metal, gap accuracy can be ensured and the resistance of the diaphragm decreases.

In this case, the crystal orientation (10
By using the single crystal silicon substrate of 0), the degree of freedom in designing a gap using anisotropic etching can be increased, and the gap can be easily formed with a variable gap (gap having a variable gap length). Can be.

Further, by using a single-crystal silicon substrate having a crystal plane orientation of (110) as the electrode substrate, the degree of freedom in designing a gap using anisotropic etching can be increased, and stable vibration characteristics can be obtained. be able to.

[Brief description of the drawings]

FIG. 1 is an explanatory plan view of an inkjet head according to a first embodiment of the present invention.

FIG. 2 is an explanatory sectional view taken along line AA in FIG. 1;

FIG. 3 is an explanatory sectional view taken along line BB of FIG. 1;

FIG. 4 is an explanatory sectional view taken along line CC of FIG. 1;

FIG. 5 is an explanatory sectional view of an ink jet head according to a second embodiment of the present invention.

FIG. 6 is an explanatory cross-sectional view of the inkjet head according to a third embodiment of the present invention in the longitudinal direction of the head for explaining a manufacturing process thereof.

7 is an explanatory cross-sectional view of the head in the longitudinal direction, following FIG.

FIG. 8 is an explanatory cross-sectional view of the head in the same direction.

FIG. 9 is a cross-sectional explanatory view similar to FIG. 7;

FIG. 10 is an explanatory plan view of a conventional ink jet head.

FIG. 11 is a longitudinal sectional view of the head.

[Explanation of symbols]

1: diaphragm / liquid chamber substrate, 2: electrode substrate, 3: nozzle plate,
4 ... nozzle hole, 6 ... liquid chamber, 7 ... fluid resistance part, 8 ... common ink liquid chamber, 10 ... vibration plate, 21 ... concave part, 22 ... silicon oxide film, 23 ... electrode, 24 ... gap, 25 ... insulating film .

Claims (6)

[Claims] A nozzle hole for discharging ink droplets, an ink flow path communicating with the nozzle hole, a vibration plate forming a wall surface of the ink flow path, and an electrode facing the vibration plate; In an inkjet head that displaces the diaphragm with electrostatic force between the diaphragm and an electrode to discharge ink droplets from the nozzle holes, the electrode is provided on a conductive electrode substrate via an insulating layer, and the electrode is provided. An inkjet head, wherein a substrate and the diaphragm are electrically connected. 2. The ink jet head according to claim 1, wherein said electrode substrate and said diaphragm are joined without interposing an insulating layer. 3. The ink jet head according to claim 2, wherein the electrode substrate and the vibration plate are formed from a silicon substrate, and both silicon substrates are directly joined. 4. The ink jet head according to claim 2, wherein the electrode substrate and the vibration plate are formed from a silicon substrate, and both silicon substrates are eutectic bonded via a metal. 5. The ink jet head according to claim 3, wherein the electrode substrate has a crystal plane orientation (100).
An inkjet head, characterized in that it is a single-crystal silicon substrate. 6. The ink jet head according to claim 3, wherein the electrode substrate has a crystal plane orientation (110).
An inkjet head, characterized in that it is a single-crystal silicon substrate.